Compliant constant-force mechanism and devices formed therewith
AssigneesPurdue Research Foundation, Delco Electronics Corporation
InventorsAshok Midha, Morgan Daniel Murphy, Larry L. Howell
Life of this patent
Estimating the term…
Abstract
A compliant mechanism is configured to generate a substantially constant output force in response to an input in the form of a linear displacement. The compliant mechanism is a slider mechanism whose members and their interconnects cooperate to generate a biasing force that causes the slider mechanism to generate a substantially constant output force that is substantially parallel to the linear path of a reciprocable member in response to the displacement of the reciprocable member along the linear path. To achieve the above functional characteristics, the slider mechanism is composed of structural elements, one or more of which is compliant.
Claims32
A compliant mechanism that generates a substantially constant output force in response to an input in the form of a linear displacement, the compliant mechanism having a four-bar slider mechanism comprising:
- a base member forming a frame of the slider mechanism;
- a first segment adjacent the base member, the first segment constituting a crank of the slider mechanism;
- a first connector pivotably interconnecting the first segment to the base member;
- a second segment adjacent the first segment, the second segment constituting a connecting rod of the slider mechanism;
- a second connector pivotably interconnecting the second segment to the first segment;
- a reciprocable member constituting a slider of the slider mechanism, the reciprocable member being limited to reciprocating movement along a solitary linear path that is spatially fixed relative to the base member, the input to the slider mechanism being the displacement of the reciprocable member along the linear path;
- and
- a third connector pivotably interconnecting the second segment to the reciprocable member;
- wherein at least one of the first, second and third connectors forms at least a portion of a means for biasing the first and second segments to be collinear with the linear path of the reciprocable member, the biasing means having a null position when the first and second segments are collinear so as to generate a torsional moment about the reciprocable member of approximately zero when the first and second segments are collinear;
- and
- wherein the lengths of the first and second segments are such that the biasing means causes the slider mechanism to generate a substantially constant force output parallel to the linear path of the reciprocable member in response to the displacement of the reciprocable member along the linear path.
A compliant mechanism that generates a substantially constant output force in response to an input in the form of a linear displacement, the compliant mechanism having a four-bar slider mechanism comprising:
- a base member forming a frame of the slider mechanism;
- a crank adjacent the base member;
- a first connector pivotably interconnecting the crank to the base member;
- a connecting rod adjacent the crank;
- a second connector pivotably interconnecting the connecting rod to the crank;
- a reciprocable member constituting a slider of the slider mechanism, the reciprocable member being limited to reciprocating movement along a solitary linear path that is spatially fixed relative to the base member, the input to the slider mechanism being the displacement of the reciprocable member along the linear path;
- and
- a third connector pivotably interconnecting the connecting rod to the reciprocable member;
- wherein at least one of the first, second and third connectors forms at least a portion of a means for biasing the crank and the connecting rod to be collinear with the linear path of the reciprocable member, the biasing means having a null position when the crank and the connecting rod are collinear so as to generate a torsional moment about the reciprocable member of approximately zero when the crank and the connecting rod are collinear;
- wherein the base member and the reciprocable member are rigid;
- and
- wherein the lengths of the crank and the connecting rod are such that the biasing means causes the slider mechanism to generate a force output parallel to the linear path of the reciprocable member in response to the displacement of the reciprocable member along the linear path, the force output deviating not more than about 3.2 percent during a displacement of at least 40 percent of the length of the linear path.
Dependencies are inferred from the claim text.